Lecture 3 Flashcards
1
Q
A
2
Q
what is the Effect of Change in Lung Volume on Airway Resistance
A
- As lung volume increases the alveolar septa will becomes stretched and will apply tension to airway walls
- Will dilate airways and reduce resistance
3
Q
Where is smooth muscle located in the respiratory tract?
A
- Trachea- Trachealis m.
- Bronchi and
- bronchioles
4
Q
- what does the smooth muscle do in the respiratory tract?
- What happens when parasympathetic system is activated?
- sympathetic system?
A
- Regulates airway diameter
- Parasympathetic system – constrict
- Sympathetic system – dilate
5
Q
what receptors are part of sympathetic system?
A
Beta 2
6
Q
what are some inflammatory mediators that cause constriction to respiratory tract?
A
•Histamine and leukotrienes
7
Q
what can dilate the airways?
A
- Nonadrenergic noncholinergic pathway
- Vagus;
- Nitric oxide
8
Q
- extrathoracic compression occurs during?
- give examples
A
- inspiration
- •Nares, pharynx, and larynx narrowing
•Example - Laryngeal hemiplegia – “roaring” - horse; inspiratory stridor – dog
9
Q
- when are intrathoracic structures compressed
- give an example
A
- during expiration
- Intrapleural pressure exceeds airway lumen pressure
- Cough – even greater pressure
- Example – tracheal collapse (toy dogs)
10
Q
what is happening in A
B
C
A
- a- normal
- b- thickening of alveolar wall leads to low compliance
- c- narrowing, leads to high resistance
11
Q
- whats happening in A for slow breathing
- rapid
A
- normal filling during inspiration and release in expiration
- normal filling and release during rapid breathing
12
Q
- What happens in B during slow breathing and rapid breathing
A
alveolus B with low lung compliance fills less
13
Q
What happens in C
A
- fills more slowly because its airway is partially obstructed
- receive less ventilation and will be unevenly distributed
14
Q
- Ideally - Ventilation and perfusion of the lung will……
- will there be gas exchange if alveoli are ventilated but not perfused?
A
- match
- No gas exchange
15
Q
Causes of uneven distribution (4)
A
- Regional variations in lung inflation
- Regional variations in airway resistance
- Regional variations in lung compliance
- Collateral ventilation
16
Q
what is this showing
A
Intrapleural pressure in dorsal part of chest will be more negative because of gravity
17
Q
Explain this
(need to get better explination)
A
- Compliance is different in different parts of the curve. Change in volume with change in pressure. When inspiration occurs, the change in pleural pressure will be the same in all of the regions, but because of the compliance difference, the change in V (volume) will be different in the different areas. The larger the difference between dorsal and ventral chest- the more it will affect their ventilation.
18
Q
- which animals have complete connective tissue in secondary lobules
- partial
- none
A
- Pigs and cattle – Complete
- Horse and sheep – Partial
- Dog and cat – None
19
Q
what is collateral ventilation
A
•Movement of air between adjacent lobules when a main bronchus obstructed
20
Q
- which animals have extensive collateral ventilation
- intermediate
- none
A
- Dog and cat – Extensive
- Horse and sheep - Intermediate
- Pig and cattle - None
21
Q
- why do cows, sheep and pigs have extensive no collateral ventilation
- what happens if a bronchiole is blocked?
A
- one bronchiole is connected to one alveoli
- Air Cannot move from alveoli to alveoli
22
Q
- what animals have septa in lungs
- what do septa contain
- what can they do?
A
- cow, sheep and pigs
- connective tissue
- Septa allow infection to be walled off and deter spread
23
Q
- why do dogs, cats and primates have extensive collateral ventilation
- what happens if a bronchiole is blocked
- what happens if they get an infection?
A
- bronchioles are connected
- If bronchioles are blocked off air can still go to other alveoli
- infection can spread easier because of no septa to wall off
24
Q
- Explain the septa in horses
- why do they have intermediate collateral ventilation
A
- some septa are present
- not as extensive connections between bronchioles
25
Q
how is pulmonary circulation different that systemic? (2 things)
A
- One organ must accommodate large variations in blood flow (cardiac output)
- Distribution of blood within the lung must match ventilation
26
Q
- where are pulmonary capillaries located?
- are they all perfused at rest
A
- surround the alveolus and are exposed to pressure changes in the alveolus.
- Not all
27
Q
- What is the pulmonary artery smooth muscle thickness in the pig/cow,
- horse,
- dog/sheep?
A
- Adult pig and cow – thick
- Horse – less
- Dog and sheep – least
28
Q
How does the animal increase and decrease blood flow resistance in the lungs to control the amount of blood flow?
A
- Extra-alveolar vessels are affected by the volume of the lungs- if airways are stretched, the blood vessels are stretched which lead to a lower resistance to bloodflow
29
Q
what is this diagram saying
A
- Diagrammatic representation of the extra-alveolar vessels (pulmonary artery and vein) in the bronchovascular bundle and (inset) an enlargement of the alveolar vessels (capillaries) in the alveolar septum.
- Notice that the alveolar septa are attached to the bronchovascular bundle so that they exert a radial traction on the bundle.
30
Q
- What are alveolar vessels?
- What type of pressure will affect these vessels?
- What types of activities can cause a positive pressure in the alveolus?
A
- Thin capillaries surrounding the alveoli
- Pressure in the alveolus will affect these vessels;
- e.g. coughing,
- straining or
- mechanical ventilation will result in a positive pressure in the alveolus
31
Q
- What are extra-alveolar vessels?
- What type of pressure will affect these vessels?
A
- vessels outside the alveolus
- Affected by pressure within the vascular bundle and not the alveolus
32
Q
is pulmonary vascular resistance higher or lower than systemic circulation?
A
lower
33
Q
- What is the systolic pulmonary artery pressures
- diastolic pulmonary artery pressures
- mean pulmonary artery pressures?
A
- Systolic pressure – 25 mmHg (30 mmHg)
- Diastolic pressure – 10 mmHg (15 mmHg)
- Mean Pressure – 15 mmHg (20 mmHg)
34
Q
- Where is most of the resistance encountered?
- Where is the other resistance encountered?
A
- Approximately 40% of total resistance is precapillary
- arteries and veins
35
Q
- Where is pulmonary blood preferentially distributed in quadrupeds?
- is gravity a major factor?
A
- Preferential dorsal-caudal distribution in quadrupeds
- gravity is not the major factor
36
Q
Describe how resistance varies with lung size
- lung deflation
- lung inflation
A
- Lung deflation to residual volume – there is a high resistance because extra-alveolar vessels are narrowed
- capillaries are distended
- Lung inflation beyond Functional residual capacity (FRC) flattens the alveolar capillaries, due to stretched alveolar septa increased pulmonary vascular resistance
- extra-alveolar vessels (artery) are distended
- capillaries are narrowed
37
Q
- Which species have a large amount of smooth muscle in the small arteries?
- intermediate amount?
- small amount?
A
- Large amount= Cow and pig
- Intermediate amount= horse
- small amount= Dog and sheep
38
Q
- Which substances vasoconstrict smooth muscle?
- parasympathetic or sympathetic nervous system does this?
- vasodilate?
- parasympathetic or sympathetic nervous system does this?
A
- Epinephrine and norepinephrine vasoconstrict
- Sympathetic
- nitric oxide vasodilates
- Parasympathetic
39
Q
- Why does the magnitude of response vary with species?
regarding the neural/humoral influence on pulmonary blood flow?
A
The more smooth muscle a small artery has the more it can constrict and cause a higher change in pressure
40
Q
What are the vasodilators? (4)
A
- NO, nitric oxide
- PGI2, prostacyclin
- βAR, beta-adrenergic receptor
- MR, muscarinic receptor
The small + and – signs, or their combination, represent the weight of the effect that the agent or receptor produces on its side of the scale. –, No effect;
41
Q
What are the vasoconstrictors? (4)
A
- ETA, endothelin A receptor
- ETB, endothelin B receptor
- αAR, alpha-adrenergic receptor
- PDE5, phosphodiesterase-5
42
Q
How does the animal increase and decrease pulmonary vascular resistance?
A
- increase- by vasoconstricting
- decrease- by vasodilating
43
Q
- How is nitric oxide released?
- how can it be administered therapeuticly
- what disease can it be used for?
A
- Released by vascular endothelium during exercise
- as nitroglycerin
- temporary relief of pulmonary hypertension
44
Q
- what is sildenafil
- what does it do?
- what disease and species can it be used for
A
- Phosphodiesterase-type 5 inhibitor
- Pulmonary vasodilation
- May be effective in the dog with pulmonary hypertension
45
Q
Alveolar Hypoxia will lead to pulmonary vasoconstriction or dilation?
A
very potent vasoconstrictor
46
Q
- what happens in Hypoxic pulmonary vasoconstriction
- will the Magnitude of this response vary with species?
A
- Poorly ventilated alveoli develop a low oxygen content
- Vasoconstriction redistributes blood flow to well ventilated alveoli
- will vary betweep species
- Cows and pigs have more smooth muscle, can accept a higher pressure because the arteries will not stretch as much
47
Q
What does Generalized lung hypoxia lead to?
A
generalized vasoconstriction = pulmonary hypertension
48
Q
Why does the body do hypoxic pulmonary vasoconstriction ?
A
This is used to keep a balance between ventilation and perfusion
49
Q
- What is Brisket disease?
- What happens during it?
A
- Brisket disease is a right heart problem because when cattle are taken up into high altitudes with a very low pressure.
- O2 has difficulty moving high to low pressure.
- In response, the pulmonary artery vasoconstricts in order to redistribute blood flow to the well ventilated alveoli(for maximal gas exchange).
- The right ventricle has to pump against this tremendous increase in pressure and thus right heart failure occurs.
- Get edema in the brisket
50
Q
- which animals can acclimate to living at a higher altitude?
- why?
A
- Llama and sheep are able to acclimate
- because can release more nitric oxide in lungs (vasodilation)
51
Q
What happens in EIPH- Exercise Induced Pulmonary Hemorrhage
A
- Cardiac output increases during exercise up to 6-8X normal
- All of the blood must pass through the lung
- Pulmonary vascular resistance starts to decrease
- Vessels dilate and closed vessels open
- Flow induced release of nitric oxide from endothelium
- Capillaries will rupture because increased pressure in lungs
- Blood will leak into alveolus
52
Q
- Why is the horse most at risk for EIPH?
- What happens to left atrial pressure?
A
- Horse cannot reduce resistance in vessels enough to keep pressure at reasonable level
- increased left atrial pressure
53
Q
What is this showing?
A
pressures go up a lot!
54
Q
- Where does the bronchial circulation originate from?
- How much cardiac output is used here?
- What does it supply?
A
- Originates from the aorta
- cardiac output= 1 to 2%
- Supplies airways and interlobular septa
55
Q
- Extrapulmonary airway (trachea) circulation drains into
- Intrapulmonary airway circulation drains into
A
- azygous vein
- pulmonary vein
56
Q
in cattle, sheep, pigs and horses bronchial circulation also supplies?
A
visceral pleura (attached to outer surface of lung)
57
Q
During inspiration
- what happens to intrapleural pressure?
- right atrial pressure
- venous return and right ventricular filling
- pulmonary vasculature
- blood in lungs
- capillary flow
- systemic arterial pressure
A
- Inspiration decreases intrapleural pressure
- Reduces right atrial pressure
- Increases venous return and right ventricular filling
- Expands compliant pulmonary vasculature
- Blood pools in the lung, veins do not empty
- Capillary flow increases then decreases
- Systemic arterial pressure decreases transiently
58
Q
During expiration what happens to
- intrapleural pressure
- venous return to right atrium
- blood in intrapulmonary veins
- systemic arterial pressure
A
- Increase intrapleural pressure
- Decrease venous return to the right atrium
- Intrapulmonary veins empty into left atrium
- Systemic arterial pressure transiently increases
